Effects of Organic Intercalation on Lattice Vibrations and Superconducting Properties of 2H-NbS₂

Abstract

The heat capacity, resistivity and superconductivity of layered compound 2H-NbS₂ intercalated with organic molecules have been studied. Heat capacity data show that upon intercalation the superconducting transition temperature decreases from 6.1 K to 2.1–4.1 K and both the Debye temperature and coefficient of electronic specific heat decrease. The temperature dependence of the resistivity measured along the layer plane is also influenced by intercalation. Experimental results are discussed in terms of nearly two-dimensional characters of conduction electrons and phonons. The electron-phonon coupling constant and the electronic density-of-states at the Fermi energy N(0) are estimated. It is shown that N(0) for intercalation compounds is able to be interpreted by the two-dimensional electronic nature.